Process of preserving wood.



W. A. CECIL. PROCESS FOR PRESERVING woon.

APPLICATION FILED SEPT. 25, I9I6.

7 II I I MII .I I -..I IIIIIIII III. IIIIHIIIIWII II 5 MWHHHWIIHIHIIIIATTORNEY WITNESSES W. A. CECIL.

PROCESS FOR PRESERVING woon'I APPLICATION FILED SEPT.25, 1916.

l ,.@g Patented Jan. 15, 1918.

2 SHEETS-SHEET 2- INVENTOR ATTORNEY nr sas Iranian orario,

WILLIAM A.' onen., or nvansviLLE, munita, AssIGNoR on ONE-Herr 'roaonnnfr n.

WILLIAMS, or nvnlvsvrLLE, INDIANA. f i

PROCESS FOR RESERVING WOOD.

l Application led S)eptember 25, 1916. Serial No. 122,125. l

To all whom t may concern:

, Be it known that l, WILLIAM A. Cnam, a citizen of the United States,residing at Evansville, in the county of Vanderburg and State ofIndiana, have invented'certain new and useful Improvements in Processesfor Preserving Wood, of which the followin is a specification.

y invention relates to a new and improved method of preserving wood byimpregnating the Ysame with preservative fluids, and especially to a newand improved process for preserving railroad cross ties, pilings,structural and mine timbers, street paving blocks, etc., in which anypreservative fluids may be used either singly or in admixture regardlessof di'erence of speciic gravities, while the pressureand the temperatureof the fluids in the impregnating cylinder or retort are automaticallycontrolle'd by means of a system ofjcirculating pipes, and speciallyconstructed automatically and mechanically operated valves which are soarranged that a uniform rise of pressure of the iuid in the impregnatingcyllnder is accomplished, this process being in part divisional matterfrom the application which eventuated into Patent No. 1,178,132, grantedto me April 4, 1916,

As is well known, the heretofore generally used method of woodpreservation by injecting chemical preservatives into the wood hasconsisted,` of placing the Wood to be treated in a .receptacle or retortcapable of being closed air and liquid tight. lf the wood belnotsulhciently dry to permit of its dit thorough saturation withoutsteaming, steam is admitted to the retort to accomplish the desiredsteaming and is maintained until the temperature attains the desiredpoint, generally about 250 degrees Fah.

This temperature is fmaintained until the.

wood is heated sufficiently to permit the moisture being drawn from thepores and cells thereof in the form of vapor, and by vacuum, a vacuumpump being coupled with the retort and 'started subsequent to theclosing of thev steam supply. This vacuum pump is operated until avacuum equal to 22 to 25 inches of mercury at sea level is drawn, thisvacuum being maintained for thirty minutes to one hour, or for any timethat the operator judges necessary to draw a sufficient amount ofmoisturefrom the wood to allow injection of the required volume of thepreservative fluid.

Next, without admitting air to the retort or otherwise breaking thevacuum, the preservati-ve fluid is admitted to the retort until the sameis filled and all of the wood completely submerged. The `outlet valvesare maintained closed and more liquid is pumped into the retort so thatthe hydrostatic pressure in the retort is raised and thus the liquidforced into the wood. In some cases a separate closed tank or receiveris connected by a large pipe to the retort. The general practice hasbeen to .place this receiver so that when the retort is full of thefluid, the level of the fluid in the receiver or tank is somewhat belowthe top, thus leaving an empty space into which air is pumped underpressure. As the pressure of the air is increased the pressure upon theliquid is communicated from the closed tank or receiver through theconnecting pipe to the fluid in the retort until the required pressureis attained in the retort; gages or recording instruments generallybeing provided to determine the exact Working conditions, and thepressure being maintained until a sufficient amount of the preservativeis forced into the wood.

lin the use of the above outlined processes, there has never beenany'circulation of the preservative fluids in the retort except for thepurpose of maintaining emulsions of more orsless immiscible fluids, suchas zinc, chlorid and creosote, but the liquids have in all cases beenpermitted to lie quiet and in a dead state in the retort whilemaintained under pressure; By this maintenance of the dead pressurewithin the retort, and through 'the consequent lack of movementand'circulation of the uid, the liquid or treating fluidvaries in itstemperature in Jche various parts of the retort, and especially in eX-posed locationsl the fluid becomes too cold for proper penetration, thuscausing a different absorption of the fluid by` the timber in di'erentparts of the retort even when tlie timber is of the same species.

Further than this, to accomplish the most successful treatment of thetimber, the pressure in the retort is to be raised at a uniform rate andthe rapidity of increase of titi till

pressure in the retort should only be such as will compensate for theincrease of the resistance to the preservative fluid as the samepenetrates into the wood and through the gradual filling of the pores orcells .sure is attained. To fulfil this requirement,

it has heretofore been necessary for the operator to stand at the pumpalmost continually during the period of raising the pressure, and, atsuch times as he judged proper, to increase the pressure by increasingthe speed of the pump, or where pneumatic' pressure, instead ofhydraulic, is used the pressure has been controlled by carefullyregulating the amount of air admitted to the air receiver, and thenagain under some circumstances the desired rises in pressure have beenaccomplished by bringing the pressure up in steps of 25 poundsat a timeand practically every fifteen minutes. All of these methods areunsatisfactory as they depend entirely upon vthe attention of and manualmanipulation by the operator, and any neglect or failure to observe theniceties of manipulation is conducive to erratic penetration. Also, itis under some circumstances requiredathat preservative chemicals suchcoal-tar creosote a1id?refined coal-A tar, coal-tar creosote and watergas tar, coaltar creosote and water gas creosote, coaltar creosote andcrude oil, coal-tar creosote and zinc chlorid solution, and etc. be usedand except in the case of emulsions of creosote and zinc chloridsolutions, no attempt has heretofore been made to assure perfectmixtureof the preservative chemicals. As the result, it is by no means certainthat the different ingredients. will remain mixed in the proper solutionso that' the proper proportion of each chemical will be carried into thepores of the `Wood but the natural tend.

ency is for the chemicals to separate and for one chemical to have abetter penetration than the remaining chemical or chemicals of thesolution, and here it might be set forth that the proper solution andanequal distribution of -all of the ingredients throughout the entire-volume of liquid which will insure a proper penetration of the solutioncan be attained and maintained only by circulation. r i g Again, it isnot possible to entirely eX- haust the air from the cells of the woodand as the .preservative fluid is forced into the.

porcs and cells of the wood this air is liberated as is also the airwhich is used in the mixture of the emulsions of preservative fluid,which are fol the most part aerated mixtures, as the fluid is forcedinto the wood.

In all processes wherein dead pressures are maintained or circulation isaccomplished by means of a closedlcircuit apparatus, air must remain inthe retort and' it will of course be readilyapparent that this presenceof air in the retort is detrimental to uniform absorption as itinterferes with the homogeneity of mixtures of preservatives whencirculation is maintained by means of closed circuit apparatus, and insome instances the volume of air may' become'sufliciently great todisplace the fluid in the retort to such an extent that some of the woodon the top of the charge in the retort may not be entirely submerged atall times.

With the above in mind, it is a purpose of my invention to overcome theabove named and other faults of processes heretofore used, by employinga process which contemplates an open circuit circulation of the treatingfluid andthe automatic control'of the pressure of the preserving fiuid,while at the same time. permitting the use of mixtures and emulsions ofpreservatives of immiscible chemicals and maintain the same in theproper condition even though they be aerated mixtures, allowing thesuccessful use of the same by permitting the airfrom the mixtures `andany air which may be forced out of the wood to escape.

It will be understood that a number of variations might be resorted toin the apparatus to be employed in accomplishing my process, but I haveendeavored to illustrate only one possible form which will permit theaccomplishment of the various steps of the treating action in the propercycles and intervals.

In the drawings: Y Figure 1 is a schematic view showing the retortstogether with the liquid supply tank and the circulating pipes to givethe general arrangement of the parts of the apparatus, and with section.f

Fig. 2`is'a detail view to illustrate the automatic valve and to showone forni of power and gear means which might be employed in theactuation of the same.

Fig. 3 is a view in elevation to better yillustrate the structure shownin Fig. 2.

Fig. 4 is an enlarged detail sectional view to better illustrate thestructureof the automatic pressureyalves.. 1

Fig. 5 is a detail .,view showing a dia,- phragm pressure switch whichmight be used in connection with an electric motor imparting. movementto the mechanically operated valve and which switch will automaticallystop the motor when the maximum pressure as desired is attained in theretort.

.The liquid supply tank l, which is designed to contain the supply ofpreservative liquid which is being constantly circulated portions shownin vertical of treating timber therein, has a suitable agitator locatedtherein to keep the supply of' liquid constantly agitated and mixed.

This agitator may be of any desired form but in the present instance isillustrated as an air supply pipe 3, which is run/ to the bottom of theliquid supply tank 1, and is extended along the bottom thereof where itis provided with perforations as indicated at 4, these perforationsbeing preferably extended throughout thecentire length of the portion ofthe pipe which is disposed adjacent to the bottom of the supply tankandto thus discharge air through substantially the entire volume ofliquid and disturb the ingredients of the greatest specific gravitywhich Will have settled to the bottom of this tank, thus causing theseingredients to move in an upward current through the ingredients of aleast specific gravity which vhave a tendency to rise to the top of themixture of fluid. By this arrangement of the parts, the entire body offluid is constantly agitated and the desired mixture and homogeneity ofthe same is maintained. It is obvious that this agitator will only beneeded when the preservative fluid is composed of two or morepreservatives of a more or less immiscible nature which are to be mixedto form the preservative fluid, and l therefore desire to limit its useto the conditions under which it is needed.

The retort 2, will generally be of cylindrical form but may be of any`desired shape and of dimensions to suit the particular use, this retortbeing provided with one open end, and a door 5 being adapted to beclosed over the open end and held liquid and air tight bysecuring boltsor clamps 6. A fill and return pipe 7 connects with the bottom of theliquid supply tank 1, and at A its opposite end is connected with theretort 2 at a point low down on the sides thereof. VA. suitable valve 8,preferably of the gate type, is provided to control the opening throughthis pipe 7, and the pipe is intended only to accomplish the initialfilling of the retort 2 after the timber to be treated has been placedtherein and the door 5 has been secured in place, and to permit thereturn of the preservative fluid from this retort when the treatingaction has ceased and it is desired to empty the retort so that the door5 can be opened to permit the removal of the treated timber and theplacing of untreated timber in the retort to be impregnated. t

A pressure pump 9 is installed as a part of the apparatus, and while 1have herein shown one specific form of pressure pump, and moreparticularly 'a pump of the piston type, 1 do not Wish to limit myselfto any particular pump but desire to have it understood that any kind ofpump or anyother suitable means which will supply liquid under pressuremay be used, the form of this part being that which appears to be moresuitable for plant conditions under which it will operate. A- pipe 10extendsy from the lower part of the liquid supply tank 1 to the pump 9,`and a pipe 11 is connected from thepump to the, retort 2, it beingpreferable that the pipe 11 be extended through the bottom of the retort2 and that branch discharge pipes 12, each provided with a plurality ofopenings 13, be connected with this pipe 11 to extend lthroughout thelengthJ of the retort 2 and to thus insure an even discharge of theliquid to all parts of the retort. A liquid outlet pipe 14 has aplurality of branches and these branches are each connected with theretort 2 in the upper part thereof to thus permit discharge from theretort substantially uniformly from all parts thereof, an`

automatic pressure valve 15 being connected in the vdischarge from theoutlet pi e 14, and a return pipe 16 being connecte with the automaticpressure valve 15 and led to the liquid supply tank 1 to thus allowdischarge of the liquid from the retort through the automatic pressurevalve 15 arid` back to the liquid supply tank. A branch pipe 17 isconnected to the outlet pipe 14C at one end, and at the opposite endthis branch pipe is connected with the return pipe 16, or the y.pipe 17might be lconnected directly with the liquid supply tank to dischargeinto the bottom thereof, as local conditions might require. Amechanically operated valve 18 having a specially constructed passagetherethrough is mounted in this pipe 17 to control the passage of Huidthereing constantly supplied by the pump 9, this regulation and controlof the pressure being accomplished by a gradual throttling of thepassage through the valve. n

A pipe 20 controlledby the valve 19 1s connected in the pipepll at `oneend, and its opposite end is connected with the boiler supplying steamto the pump 9, or with any other suitable means' to 'supply steamthrough this pipe and through the plurality of openings 13 in the branchdischarge pipe 12, the purpose ofrthis ste/am being to dry the Jsap orother smoisture out nof Jthe pores of the wood preparatory to theimpregnating process. l

- A pipe 21 is. connected with the upper side of the retort F2, and abranch pipe 22 is connected with this pipe 21 and isextended to connectwith any suitable source of compressed a/ir su ply, the valveA 23 beingpro vided to contr l the passage of fluid through this pipe 22. A secondbranch pipe 24, controlled by a valve 25, is connected with a vacuumpump or other suitable means which may be set in operation to exhaustthe iiid contents of the retort and to thus extract the moisture, airand steam from the retort, just prior to the introduction of theimpregnating liquid thereinto.

The pressure control valve 18, as shown in detail in Figs. 2 and 3, maybe a gatpv valve of the non-rising' stenf type with a passage throughthe same so proportioned that when opened to its full extentsubstantially all the fluid discharged into the retort 2 by the pump 9will pass through the valve.

l ber will be extended over or withdrawn from'the passage. A relativelylarge worm gear 30 is connected on this stem 29 and a transmission shaft31 has a worm 32 mounted thereon to mesh withv'theworm gear 30.

A worm gear 32 is carried on the opposite p end of the transmissionshaft 31 and a motor 33 has a worm 34 on the shaft thereof meshingwiththis worm gear 32 so that as the motor is operated rotary motion will betransmitted to the stem 29' at aA greatly reduced speed over the speedof rotation of the motor shaft. While I have shown one form of operatingmeans for the valve 18, it is obvious however, that many forms of gearand power may be used to operate this valve, and I do not wish to limitmyself to any specific gear or power but desire to use any form dotpower availa le or any geai that may be needed in any specific instance,or evenyf occasion requires, to operate valve 18 by hand.

The automatic pressure release valve shown in detail i-n Flg. 4,comprises the case Vwhich has the valve proper 26, mounted thereinbetween the connection of pipe 14 provided to form an outlet from theimpregnating cylinder or retort 2, and the pipe 16 which returns to theliquid supply tank 1, and a spring 27 is provided to bear against thisvalve 26 to exert pressure to oppose the opening of this valve andconsequently to oppose the passage of liquid from the outlet pipe 14' tothe return vpipe 16. While the spring 27 is illustrated as a simplecoilspring around the stem of the valve 26 to bear. against thereverseside thereof and against the head of the case, it will beunderstood. that by. changing this spring and substituting therefor aspring of a lighter or heavier gage, the valve 26 can be regulated toopen at varied pressures, and here it might also be stated that it mightbe dewilli1 sirable to, in some, uses, provide means whereby thepressure of uthe spring 27 may be adjusted to accommodate variousoperating conditions and to give various settings thereto without thenecessity of dismantling the parts to insert a new spring.

As is hereinbefore set forth, I have provided a motor 33 to control thevalve 18, and the circuit wires from this motor are led to a generator35, or to any other suitable source of electrical energy. Not only is itdesirable that the valve'18 be gradually closed to. consequentlygradually increase the pressure within the retort 2, but also it isdesirable that some means be provided to automatically cut out theconnection to the motor so that the valve will not be given furtheractuation after a desired maximum pressure has been attained within theretort, and to accomplish this purpose I provide the diaphragm pressureswitch, as better shown in Fig. 5, which switch 36 is connected in oneof the circuit wires to the motor 33 and is designed to automaticallystop the motor when the maximum retort pressure has beenaccomplished. Apipe 37 is vled from the retort chamber to*t connect with the diaphragmchamber 38, and in this way when pressure sufficiently strong toovercome the pressure of the spring 39 is accomplished in the retort,this pressure will be transferred through the pipe 37 to `the diaphragmchamber 38 and in consequence the switch arm 4:0 will be swung outwardlyto break the switch connection.

In the accomplishment of the process, the

timber, ties, poles, paving blocks, etc., are

loaded on trucks and run into the retort, or are otherwise placedtherein, and the doorl 5 is closed into place and is secured to make theretort 'air and liquid tight. Steam is admitted through the valve 19 andthe pipe 20, passes through pipe 11 into branch pipes 12y and isuniformly distributed throughout the interior of the retort 2y throughthe openings 13. After the wood in the retort 2 is heatedto the propertemperature, generally about 250 degrees Fah., for the necessary time,generally from one to five hours, the valve 19 is closed to shut off thesupply of steam and the steam contained in the retort 2 is blown awayuntil the pressure in the retort is at or nearly at atmosphericpressure. The blow-oil", not shown, is then closed and valve 25 inpipe-24 which leads to the vacuum pumpf is opened, thus permitting theair, moisture, and steam within the retort to be drawn out ,of theretort 2 and passed away through the vacuum pump. This operationextracts the air and moisture from the wood leaving the cells and poresthereof open and in proper condition to absorb the preserving liquid.

After a' vacuum of from ,22 to 25I or more inches ofa mercury has. beenmaintained in the interior of the retort 2, for under oraaaaeev dinaryworking conditions, from forty minfutes to one hour, the valve 8 in thepipe 7 is opened and liquid flows from the supply tank l'into theexhausted retort 2 to entirely fill this retort and completely submergethe Wood contained therein to be treated. rllhe valve 25 in the pipe 24is then closed to cut oli communication from the vacuum pump, valve 8 isclosed to cut ofi' communication from the liquid supply tank 1 to theretort 2 through the valve 7 valve 18 is opened, and pump 9 is startedin operation. The mechanical arrangement Which operates -valve 18 isthen set in operation so that the valve will be' gradually closed, or`care is taken by thetoperator to manually manipulate this valve toaccomplish the gradual closing of the passage therethrough. The pump 9takes liquid through the pipe 10 from the liquid supply tank 1, andforces this liquid through pipe 11 to?be discharged through .theopenings 13 into all parts of the retort. As the retort has been filledthrough pipe 7 the further supply of liquid thereto through the pipe 11causes the impregnating liquid to be forced through the retort 2 outthrough the pluralit of `branches in the pipe 14, thence throug the pipe17 and valve 18 back to the liquidsup ply tank 1, the pressure of thespring 'in the valve 15 acting to close comlnunication there- 'throughwhile the valve 18 is 'still open. As the valve 18 is gradually closed,the pressurein the ret/ort is raised to the maximum pressure as desired.

It is preferable that the passage through valve 18 be made of triangularshape, as shown in Fig. 2, for the reason that when the pump is started,cir ulation begins gud the full opening throu h'the valve 18 allows thefull volume o liquid sup lied to the retort 2 to pass freely through t evalve 18. As the area of outlet through valve.A

18 is gradually restricted due to the mecharical closing of the valve18, there is `a corresponding rise of pressure in the retort 2, sincethe velocity of the How of theliquid is increased about as the square ofits pressure. Therefore, to obviate the necessity of changing the speedof the gearing from the motor at frequent intervals to render theraising of the pressure in the retort 2 uniform and automatic, it isnecessary that the valve moving ata uniform speed, re-

strict a relatively larger' area of opening atv the beginning of theoperation and a gradually decreasing area as the velocity of liquid Howincreases, due t the increasing pressure in the retort 2, an hence Imake use of the triangular outlet.

'When the maximum pressure in the retort 2 is attained, the liquidpressure acting on the diaphragm of the automatic switch 36 forces theswitch arm 40 open, breaking the ttf circuit contact, and the motor isthus automatically stopped. VrIhe valve 18 will, by

matic switch has been set.

The pressure release valve 15 is set to discharge at or near the maximumpressure at which the retort 2 is operated, and thus act as a safetyvalve to relieve any excess of Huid over the lvolume that ,will bedischarged through the restricted opening of the valve 18, whichincreases in the' volume of fluid `mayxat times be caused by variationsin the speed of operation of the pump 9, and thus all danger ofexcessive or over pressure is obviated.

While I have herein shown one specific form of apparatus which isadaptable for the accomplishment of the process, and an apparatus whichWill carry out the steps thereof in proper order, it willbe understoodthat changesv in the apparatus may be made and may even be desirableunder-,various operating conditions, therefore, I do not Wish to limitmyself to any particular arrangement of the apparatus, and further donot Wish to be limited.A in so far as the process is concerned, exceptfor such limitations as the claims may impart.

I claim: t

1. rl`he method of preserving Wood which consists in treating the Woodby the circula,- tion of a preservative fluid in and through a retort inwhich the wood is placed and in and through an open circuit pipingsystem to thus provide for elimination of free air from the retort.

2. The method of impregnating Wood which consists in placing the Wood ina container, filling the container With preservative li uid, injectingvliquid into the container to e equally supplied in all parts, anddischarging liquld from\-the container at diderent oints to secure aflow through and circulation in all parts of the retort.

3. rllfhe method of impregnating Wood which consists in placing the Woodin a container, injecting liquid into the container at the bottomthereofto be equally supplied in all parts, discharging liquid from thecontainer at the top thereof and at different points to secure an equalflow through and circulation in all parts of the container, andconstricting the dischargeV to raise the pressure of liquid Within thecontainer. w

4. rIlhe method of impregnating Wood which consists in placing the woodin a retort, filling the retort with preservative 'liquid taken4 from aliquid supply, maintalning a constant supply and flow of liquid sureWill be maintained substantially con-A stant at the maximum forl whichthe auto under pressure into all parts of the retort, discharging liquidfrom the retort at dif- 'ferent points to secure an equal How throughand circulation in all parts of the retort, conductingthe dischargeliquid to the liquid supply, and agitating the liquid at the supply tobe reinjected into the retort.

5. The method of impregnating'vvood -Which consists in placing the Woodin a retort, filling the retort With preservative liquid taken from aliquid supply, maintaining a constant supply and flow of liquid underpressure into all parts of the retort,

discharging liquid from the retort at`dif-I pressure within the retortto a maximum, and maintaining this maximum pressure within .the retortfor a period of time to securevproper penetration of the liquid into theWood. f

6. The method of-preserving Wood by the use of a preservative fluidconstituting a plurality of chemical lngredients, which consists insubmerging the Wood in the iuid mixture and maintaining. a continuousiow of the fluid mixture from and to a fluid supply, and constantlymixing the preservative iuid at the fluid supply.

In testimony whereof I affix my signature in presence of two Witnesses.

, vv. A. cEoIL.

Witnesses:

ALLEN DEAN, l RAYMOND MEYER.

